• Abnormal chewing habits: Parafunctional chewing habits, e.g. bruxism (habitual grinding of teeth) and chronic persistent chewing of coarse and abrasive foods or other substance, e.g. tobacco and betel nut, etc.

• Structural defects in teeth: The structural defects, which make the tooth more vulnerable to attrition even under normal masticatory forces include—- Amelogenesis imperfecta- Dentinogenesis imperfectaIn these situations, the hardness of enamel or

dentin is much more inferior as compared to the

normal teeth and therefore, the rate of tooth wear

is high even under normal chewing pressures.

CLINICAL FEATURES OF ATTRITION

• Attrition can occur in both deciduous as well as in the permanent teeth.

• Attrition of tooth isclinically manifested by the formation of flat, smooth, shiny, well-polished facets on those surfaces of teeth which come in contact with the opposing teeth (Fig. 7.1).

• Thus, attrition often occurs on the tip of the cusps, incisal edges, on the proximal contact areas, labial surface of lower anteriors and palatal surfaces of upper anteriors.

• In advanced cases,attrition may lead to severe reduction in the cuspal height with complete wearing of enamel and flattening of the entire occlusal surface.

• When the enamel is lost on the occlusal surface, the dentin becomes attrited at a faster rate and the lesion may become cap shaped, surrounded by a rim of enamel at the periphery.

• When dentin becomes exposed it

generally becomes discolored brown.

• Attrition in the proximal surfaces of

teeth occurs due to vertical movements

of tooth within the socket during

mastication.

• Proximal surface attrition causes

transformation of proximal "contact

points" to relatively broad and flat

"contact areas".

• This type of loss of tooth structure from

the proximal surfaces may even lead to

mesial migration of teeth in the dental

arch.

• Normally, men often exhibit more severe

attritions of teeth than women.

• Exposure of dentinal tubules in severe

cases of attrition may lead to tooth

hypersensitivity.

• Pulp exposure and subsequent pain are

rare in case of attrition as the process is

generally slow, and often allows

sufficient time for formation of

protective reparative dentin.

• Attrition may also occur on the

restorations of teeth. A common

example in this regard, is the

development of shiny facets on the

amalgam filled surfaces.

• Attrition may even possibly lead to

fracture of the cusps of teeth or

restorations.

TREATMENT

Treatment of attrition is difficult; however certain things can be done to reduce

Fig. 7.1 : Attrition of tooth

further tooth wear.• Corrections of developmental

abnormalities causing traumatic occulusion.

• Correction of parafunctional chewing habits.• Protection of tooth by metal or

metalceramic crowns where structural defects (e.g. amelogenesis or dentinogenesis imperfecta) exist.

• Construction of occlusal guard, if the habit of bruxism is persisting.

ABRASION OF TEETH (FIG. 7.1A)DEFINITION

Abrasion is the pathological wearing of dental tissues or dental restorations by friction with foreign substances independent of occlusion.

ETIOLOGY AND PATHOGENESIS

Different foreign substances produce different patterns of tooth abrasion. However, the process of tooth wear is similar in every case.

Causes of abrasion

• Toothbrush abrasion• Habitual abrasion• Occupational abrasions• Abrasions by prosthetic appliances• Ritual abrasions.

Toothbrush Abrasion

• It is the most common type of abrasion and is mostly associated with faulty tooth brushing technique.

• Abrasion mostly occurs when the tooth brushing is done in horizontal brushing strokes rather than vertical strokes.

• It also occurs if excessive force is applied on the teeth during brushing.

• The condition is made even worse when an abrasive dentifrice is used.

Habitual Abrasion

• Excessive habitual chewing of betel nut, tobacco and pan, etc. causes abrasion of teeth.

• Habitual pipe smokers may develop abrasion on the incisal edges of upper and lower anterior teeth due to continuous biting on the pipe stem.

• Chronic habitual biting of pencils, bobby pins (hair grips) and threads, etc. often cause abrasion.

• Improper and habitual use of tooth prick or dental floss, etc. can cause abrasions on the proximal surfaces of teeth.Occupational Abrasion

Occupational abrasion develops when objects or instruments are habitually held between the teeth by professionals during work.• Hairdressers often grip the hairpins

between their teeth during work and this can cause tooth abrasions.

• Carpenters often keep small tools or nails between their teeth when they are at work and this type of practice cause abrasion of tooth resulting in notching on the tooth surface especially at the incisal edges of the anterior teeth.

• Similar occupational abrasions can also be seen among tailors and shoemakers.

Abrasion by Prosthetic Appliances

Faulty clasp design in removable partial denture prosthesis may also cause abrasion of tooth.

Ritual Abrasion

Ritual abrasions of tooth are uncommon nowadays and are mainly confined in Africa.

For example, ancient people used to believe in some pragmatic concepts and

Fig. 7.1 A: Abrasion of teeth

according to that they often used to mutilate their teeth with some instruments. These practices were aimed at making themselves immune from evil spirits.

CLINICAL FEATURES OF ABRASIONS

• In abrasion of tooth, the type and severity of surface wear will depend upon the duration and the type of faulty habit adopted by the person.

• Clinical manifestations differ in different types of habit, e.g. a defect in the tooth due to toothbrush abrasion will differ from that of the occupational abrasion or from the habitual abrasion.

• The abrasion produces a V shaped or wedge- shaped horizontal cervical notch on the buccal surface of teeth. The notch will have sharp angles and highly polished dentin surface.

• Toothbrush abrasions commonly occur on the cervical areas of the labial or buccal surfaces of teeth.

• Canines and premolars being the more prominent teeth are often more severely affected by abrasion.

• Teeth on the left side of the arch are more severely involved in right-handed persons and vice versa.

• Maxillary teeth are more commonly affected than mandibular teeth.

• In cervical abrasion, lesions are more often wide than deep.

• Toothbrush abrasion may also cause gingival recession.

• In pipe smokers, abrasions develop on the insical surfaces of upper and lower anterior teeth. The lesion is characterized by a well- polished notch, whose shape typically matches with the shape of the pipe stem used by the smoker.

• Abrasion caused by habitual holding of nails or needles or other small tools by the tailors or shoe makers or carpenters, etc. often produces a small, deep, well-polished 'ditch' on the incisal edge of teeth.

• Faulty use of tooth-prick or dental floss

cause loss of dentin and cementum, especially of the root surfaces on the proximal walls of teeth.

• Severe abrasion (of any type) may cause opening up of the dentinal tubules and therefore, the patient may experience sensitivity in the affected teeth due to hot and cold substances.

• Secondary or reactionary dentin usually forms on the pulpal surfaces to protect the teeth from pulp exposures.

• In untreated cases, the lesion may deepen further and it may eventually expose the dental pulp with subsequent of pulpitis and other associated manifestations.

TREATMENT

Avoidance of abnormal brushing habits prevent abrasions, however in already developed cases, restorative treatment helps to keep the tooth surface intact and also it prevents further tooth wear.

TOOTH ABFRACTIONDEFINITION

Abfraction is the pathologic loss of tooth enamel and dentin caused by biomechanical loading forces.FORCES CAUSING ABFRACTION

• Static forces: Produced during

swallowing, tongue thrusting and

cleanching.

• Cyclic forces: Forces produced during

chewing. These forces cause repeated

flexure and

ultimate material fatigue to the affected

tooth at locations away from the point of

loading.

CLINICAL FEATURES

• Abfraction causes breaking down of enamel on the buccal surface of tooth.

• People with open bite or very deep class 1 cavity are more prone to develop abfraction of tooth.

• Sensitivity of tooth, sign of traumatic occlusion and wearing on the occlusal surface are often seen.

• Stress lines on the tooth surface and sometimes fracture of the tooth may occur.

• Repeated failure of restorations on the cervical area due to damaging lateral forces.

EROSION OF TEETHDEFINITION

Erosion can be defined as progressive irreversible loss of hard dental tissues by some chemical process that does not involve bacterial action (Fig. 7.1 B).

In erosion, dissolution of the mineralized tooth structure occurs upon contact with acids, which are introduced into the oral cavity either from intrinsic sources or from extrinsic sources. However, it is important to note that erosion may render the teeth more susceptible to other retrogressive changes like attrition and abrasion, etc.

ETIOLOGIC FACTORS FOR EROSION

(A) EXTRINSIC FACTORS

Acidic Foods and BeveragesAcids from extrinsic sources (source is

outside

the body), which can cause erosion of tooth

usually, come from acidic beverages,

foods,

and medications, etc. or from the

environment

itself.

• Most of the fruits and fruits juices have

a low pH and these can cause erosion of

tooth if consumed regularly.

• Carbonated soft drinks and sports

drinks are also very acidic in nature and

frequent consumption of these drinks

may result in erosion of tooth.

• Rate of erosion of tooth is proportional

to the amount and frequency of

consumption of acidic beverages/foods.

The erosive potential of acidic

foods/beverages can be reduced if:

• They contain large amount of calcium,

phosphate and fluoride, etc. which help

in tooth remineralization.

• If tooth brushing is done after every

intake of beverage.

• If drinks are taken by a straw rather

than from a glass (it minimizes contact

time with tooth).

MedicationsSome medicines can be highly acidic in

nature (e.g. vitamin C and hydrochloric

acid preparations, etc.) and they can cause

erosion of teeth when chewed or kept in

the mouth for a long time prior to

swallowing.

Occupa t ion a I eros ions• Occupational erosions are seen among

workers who often come in contact with

acids at their place of work. Commonly

vapors of different acids, e.g. chromic

acid, hydrochloric acid, sulphuric acid

and nitric acids, etc. are released into

the work environment during industrial

electrolyte process. These vapors can

cause erosion of teeth, on those

surfaces, which are normally exposed to

the atmosphere (incisal third of

incisors).The systemic diseases associated with erosion

of teeth• Gastroesophageal reflux disease (GERD)

• Chronic alcoholism• Pregnancy• Esophagitis• Gastritis• Peptic ulcer• Hyperparathyroidism

Fig. 7.1 B: Erosion of tooth

• Bulimia• Nervous system disorder.

• Commonly the workers involved in manufacturing of lead acid batteries or sanitary cleansers or soft drinks, etc. or those who are working in galvanizing or plating factories often develop occupational erosions of teeth.

• Occupational wine tasters often have erosion in their teeth.

• Swimmers who practice regularly in the pools can have erosion of their teeth if the pool water contains higher concentrations of acids.

(B) INTRINSIC FACTORSThe intrinsic pathology of erosion means the acids are produced within the body and cause erosion of tooth. This type of erosion occurs in cases of certain systemic diseases, which cause increased vomiting and regurgitations of bowel contents into the mouth. When the gastric acids (having pH as low as below 1) come in contact with the teeth extensive erosions occur.

CLINICAL FEATURES OF EROSION

• Acids from extrinsic source cause erosion on the labial or buccal surfaces of teeth and acids from intrinsic source cause erosion on the lingual or palatal surfaces of teeth.

• The commonest site of dental erosion is the gingival third of the labial surfaces of maxillary incisors.

• In chronic severe cases of erosion, the disease can involve even the proximal surfaces of teeth besides involving the labial and lingual surfaces.

• Clinically the condition is manifested by shallow, broad, 'scooped-out' concavities on the enamel with highly polished surfaces.

• The shape and size of the lesion may vary considerably and it usually involves multiple teeth.

• There will be cupping of occlusal surfaces of molar teeth or grooving of the incisal edges of anterior teeth with

exposure of dentin.• Increased incisal translucency of teeth also

¥

occurs.• In severe erosion there may be loss of

entire buccal cusp of the molar teeth which results in a 'ski slope' like depression of the tooth that extends from lingual cusp up to the buccal cervical area.

• Erosion causes raised amalgam restorations above the level of the tooth surface. The remaining part of the tooth looks clear, polished and unstained.

• Erosion causes loss of tooth structure from the palatal surfaces of upper anteriors, which results in increased concavity.

• Amalgam restorations often have a clean, nontarnished appearance due to action of acids on the metal surface.

• Preservation of enamel "cuff" on the gingival crevice is common.

• Loss of enamel often causes hypersensitivity in the teeth and it may also trigger secondary dentin formation; however the tooth sensitivity occurs only in cases of rapid erosions. Sensitivity of tooth does not occur in slowly progressing erosions; as there is enough time for formation of reactionary dentin in the tooth, which protects the pulp.

• Severe cases of erosion however can cause exposure of pulp in deciduous teeth.

• Microradiography shows a gradual demineralization of surface enamel to a depth of about 100 ]im.

TREATMENT

Preventive treatment: Identification of etiology is important in the management of erosion. Proper counseling is needed in case the patient is consuming excessive amount of carbonated beverages.

Patients with chronic vomiting or GERD are to be referred to concerned specialists for initiation of proper therapy.

Restorative treatment: Depending upon the degree of tooth wear, restorative treatments can be undertaken to maintain the structural integrity of the eroded teeth.

ROLE OF SALIVARY FUNCTION IN THE

PREVENTION OF DENTAL EROSION

Salivary function is an important factor in

the prevention of erosion since buffering

action of saliva can neutralize the intrinsic

and extrinsic acids in the oral cavity and

this in turn prevents erosion of teeth.

Moreover, mineral ions in saliva can cause

remineralization of the enamel damaged

by the acids.

However, there is a relationship

between the salivary flow rate and its

buffering capacity (i.e. buffering capacity

of saliva increases as the flow rate

increases).

Therefore, if the salivary flow rate is

decreased either due to some medications

or disease, etc. there will be more and

more erosion of teeth.

It has also been found that if there is an

increase in the citric acid and mucin

content in the saliva, these agents prevent

the precipitation of mineral ions from

saliva and hampers the remineralization

process.

RESORPTION OF TEETH

DEFINITION

Resorption of teeth can be defined as a

chronic progressive damage or loss of

tooth structures (mostly roots of the teeth

or sometimes crowns) due to the action of

some specialized cells called odontoclasts.

Resorptions sometimes occur as a

physiological phenomenon as in case of

root resorption of deciduous teeth. 1

lowever, resorptions can also occur in a

number of conditions as a pathological

entity in relation to the permanent

dentition.

Resorption is generally associated with

some attempt at repair by the apposition

of cementum or bone and the involved

tooth may occasionally become ankylosed

to the surrounding bone.